Digital printing methods, such as inkjet printing with aqueous inks, can be used for the printing of solid surfaces and offer a number of potential benefits over other printing methods, such as transfer printing and screen printing. Aqueous inkjet inks are inherently safer than reactive UV inks and inks whose primary vehicle is a solvent. Inkjet printing furthermore allows visual effects such as tonal gradients that cannot be practically achieved with the other printing means for solid surfaces.
Both dyes and pigments have been used as colorants for inkjet inks and both have certain advantages. Pigment and disperse dye inks are advantageous because they tend to provide more water-fast and light-fast images than soluble dye inks. Aqueous pigment and disperse dye inks however do not readily adhere to solid media with low surface energies, such as solid plastic media, and when applied to solid plastic media can exhibit unsatisfactory durability, weatherability, and rubbing or scratch resistance.
Pretreatment fluids can be used to prime media before ink colorants are jetted on the media to provide bleed and coalescence control as well as improve adherence and durability. However, pretreatment fluids due not readily adhere to low-porous and non-porous media with low surface energies and can exhibit poor water and solvent durability that can be unsatisfactory for outdoor signage.